Ceiron Thomas was deputising for the injured Stephen Jones
Scarlets: (10) 35
Tries: C Thomas, B Davies, Bater, M Jones, James
Cons: C Thomas (2)
Pens: C Thomas (2)
Dragons: (6) 11
Tries: K Morgan
Pens: Sweeney (2)
A second-half onslaught saw the Scarlets climb above the Dragons as the bottom Welsh Magners League side with a bonus-point win at Stradey Park.
Ceiron Thomas' 10 first-half points gave the home side the advantage, two Ceri Sweeney kicks keeping it close.
But yellow cards for Richard Wilkes and Aled Brew cost the visitors dear, Barry Davies and James Bater getting tries.
The miscreants returned, but Mark Jones and Dafydd James secured the win before Kevin Morgan got a consolation try.
The victory sets the Scarlets up for next Friday's Heineken Cup quarter-final game with Munster in Llanelli, while the Dragons will have to regroup before Saturday's European Challenge Cup quarter with Brive in Newport.
The highlight of the opening period was provided by veteran Dragons flanker Colin Charvis.
We've been building momentum slowly for the last few weeks and I'm delighted with that
Scarlets coach Phil Davies
A breathless period of line-to-line action culminated with Scarlets centre Gavin Evans flying for the line.
With a try looking certain, Charvis belied his 34 years to track back with a desperate, full-length tackle to haul down the young Wales three-quarter in full flow.
But the home side got the first try on the board when a kick from half way took a wicked bounce to deceive the unfortunate Morgan.
Thomas was quickly on hand to hack through and beat Brew to the touchdown.
Sweeney missed a straightforward penalty, but made amends by getting the Dragons on the board with a 32nd-minute kick.
Charvis battled gamely in a losing Dragons side
The visitors were sleeping from the restart, though, and immediately conceded a penalty for Thomas to stretch the Scarlets' lead back out to seven.
To compund their problems, replacement hooker Wilkes was somewhat harshly yellow-carded for offside at a ruck, meaning that passive scrums resulted for the duration of the sin bin.
Sweeney landed a second penalty to make it 10-6, but straight after the break his side were down to 13 men when Brew was sin-binned for killing the ball in front of the posts.
Wilkes returned for the Dragons, but the 14 men could not hold out as man-of-the-match Regan King set up Davies with a quality inside ball.
The full-back, still with plenty to do, stood and stepped opposite number Morgan before showing the pace to go in at the corner.
We're conscious that there's a big game next week and I'm sure we can recover quickly
Dragons coach Paul Turner
With the Dragons still a man short, Thomas landed another penalty, before Morgan again failed to deal with a wicked bounce from a kick through.
Scarlets captain Bater was the first to get boot to the loose ball, and the flanker had the pace to follow through for the third try.
The bonus-point try came from turnover ball in midfield, the ball spun quickly to Wales wing Jones who made the most of the space to cross in the corner.
A strong charge from Matthew Rees helped set up the fifth try, Thomas nearly blowing a huge overlap with an inaccurate pass that bounced favourably for replacement wing James to finish clinically.
Replacement back-rower Nic Fitisemanu gave the Dragons some go-forward, allowing Morgan to show his class by taking an outside break in midfield for a late score.
But it will be the Llanelli team who go into next weekend's European showdowns riding the crest of a wave.
Scarlets director of rugby Phil Davies:
"We've been building momentum slowly for the last few weeks and I'm delighted with that result.
"We had the balance right in bringing back a few of our international players, we had the consistency in selection and were able to create and take our opportunities.
"There was no eye on next week. We have the utmost respect for the Dragons and knew we had to perform."
Dragons coach Paul Turner:
"It's clear to see that we were second best on the night, we had early injuries to Adam Black and Ben Daly and never recovered.
"We felt that a great defensive performance could win us the game, but they killed us off with some great tries.
"We're conscious that there's a big game next week and I'm sure we can recover quickly, despite the disappointment. But we have to play far better than this."
Scarlets: B. Davies, M. Jones, King, G. Evans, Daniel, C. Thomas, Peel, I. Thomas, Gravelle, Manu, Afeaki, MacLeod, Bater, G. Thomas, N. Thomas.
Replacements: James for Daniel (47), Stoddart for C. Thomas (79), L. Davies for Peel (65), J. Davies for I. Thomas (79), Rees for Gravelle (50), A. Jones for Afeaki (58), Mills for G. Thomas (70).
Dragons: Morgan, Wyatt, Emerick, P. Dolman, A. Brew, Sweeney, Cooper, Black, Daly, Harrison, Charteris, Sidoli, Charvis, Ringer, Owen.
Replacements: A. Thomas for Emerick (75), Maule for P. Dolman (66), Walker for Cooper (69), Corsi for Black (43), Wilkes for Daly (19), Hall for Charteris (64), Fitisemanu for Owen (64).
Yellow cards: 37: Richard Wilkes; 42: Aled Brew
Referee: Phil Fear (WRU)